[FEA] static_map::insert_if

[PointKernel]

Is your feature request related to a problem? Please describe.
Given a set of key/value pairs, insert pair[i] if predicate of stencil[i] returns true. The API should be similar to static_mulimap::insert_if:

  /**
   * @brief Inserts key/value pairs in the range `[first, last)` if `pred`
   * of the corresponding stencil returns true.
   *
   * The key/value pair `*(first + i)` is inserted if `pred( *(stencil + i) )` returns true.
   *
   * @tparam InputIt Device accessible random access input iterator where
   * `std::is_convertible<std::iterator_traits<InputIt>::value_type,
   * static_map<K, V>::value_type>` is `true`
   * @tparam StencilIt Device accessible random access iterator whose value_type is
   * convertible to Predicate's argument type
   * @tparam Predicate Unary predicate callable whose return type must be convertible to `bool` and
   * argument type is convertible from `std::iterator_traits<StencilIt>::value_type`.
   * @param first Beginning of the sequence of key/value pairs
   * @param last End of the sequence of key/value pairs
   * @param stencil Beginning of the stencil sequence
   * @param pred Predicate to test on every element in the range `[stencil, stencil +
   * std::distance(first, last))`
   * @param stream CUDA stream used for insert
   */
  template <typename InputIt, typename StencilIt, typename Predicate>
  void insert_if(
    InputIt first, InputIt last, StencilIt stencil, Predicate pred, cudaStream_t stream = 0);

Additional context
Required by cudf semi/anti join refactoring

[vyasr]

@PointKernel can you assign me? I've already started looking into this.